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brood to be numbered by thousands. These have afforded an unlimited 
supply of extremely interesting microscopic objects, but it is perhaps 
needless to say that every precaution has been taken to guard against 
the escape of those not required for mounting. 
It has been remarked by my friend that if an overgorged tick 
drops of its own accord from a horse upon the dusty road it at once 
makes direct for the grass, leaving a characteristic and well-marked 
track at right angles to the roadside ; but if on the other hand a tick 
is forcibly removed from the animal and thrown upon the road, it goes 
by a straight line back to him again. Eyes being mostly absent, a 
query arises by what sense is it so unerringly directed. In 1881 it 
was observed by Dr. Gr. Haller, “ that near the hind margin of the 
terminal joint of the first pair of feet in locodes Ricinus there are two 
foramina which are covered by a transparent membrane, within which 
are found chitinous hairs and otoliths, presenting an extraordinary 
resemblance to the auditory arrangements of the Crustacea.”* An 
organ similar to this, but furnished with a ring of external sensory 
hairs, is found likewise situated on the front legs of these cattle ticks, 
being quite distinct even in their earliest stage as soon as hatched, but 
I have observed that whereas in the larval condition, when possessed 
of six legs, all are used for purposes of locomotion, when the adult 
stage is reached and an additional pair of legs is acquired, the second, 
third, and fourth pairs only are employed in walking, the first pair 
being entirely withdrawn from the ground by the altered shape of the 
anterior portion of the body, and thenceforth kept in constant move- 
ment waving to and fro above and in front of the head as if they had 
taken upon themselves the functions of antennae. The existence of a 
pair of sensory organs on the terminal joints of the palpi is more 
obvious, and is seen in the figures of most writers on the subject.! 
* This Journal, 1881, p. 449. 
t For observations confirming those recorded in this communication, see the 
Report of the Proceedings of the Society at the June Meeting ( posted , p. 574). 
